/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.procedure2;

import java.util.concurrent.DelayQueue;

import org.apache.hadoop.hbase.procedure2.util.DelayedUtil;
import org.apache.hadoop.hbase.procedure2.util.DelayedUtil.DelayedWithTimeout;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Runs task on a period such as check for stuck workers.
 *
 * @see InlineChore
 */
@InterfaceAudience.Private
class TimeoutExecutorThread<TEnvironment> extends StoppableThread {

    private static final Logger LOG = LoggerFactory.getLogger(TimeoutExecutorThread.class);

    private final ProcedureExecutor<TEnvironment> executor;

    private final DelayQueue<DelayedWithTimeout> queue = new DelayQueue<>();

    public TimeoutExecutorThread(ProcedureExecutor<TEnvironment> executor, ThreadGroup group, String name) {
        super(group, name);
        setDaemon(true);
        this.executor = executor;
    }

    @Override
    public void sendStopSignal() {
        queue.add(DelayedUtil.DELAYED_POISON);
    }

    @Override
    public void run() {
        while(executor.isRunning()) {
            final DelayedWithTimeout task = DelayedUtil.takeWithoutInterrupt(queue);
            if(task == null || task == DelayedUtil.DELAYED_POISON) {
                // the executor may be shutting down,
                // and the task is just the shutdown request
                continue;
            }
            LOG.trace("Executing {}", task);

            // execute the task
            if(task instanceof InlineChore) {

                /********
                 * TODO_MA 马中华 https://blog.csdn.net/zhongqi2513
                 *   注释：
                 */
                execInlineChore((InlineChore) task);

            } else if(task instanceof DelayedProcedure) {
                execDelayedProcedure((DelayedProcedure<TEnvironment>) task);
            } else {
                LOG.error("CODE-BUG unknown timeout task type {}", task);
            }
        }
    }

    public void add(InlineChore chore) {
        chore.refreshTimeout();
        queue.add(chore);
    }

    public void add(Procedure<TEnvironment> procedure) {
        LOG.info("ADDED {}; timeout={}, timestamp={}", procedure, procedure.getTimeout(), procedure.getTimeoutTimestamp());
        queue.add(new DelayedProcedure<>(procedure));
    }

    public boolean remove(Procedure<TEnvironment> procedure) {
        return queue.remove(new DelayedProcedure<>(procedure));
    }

    private void execInlineChore(InlineChore chore) {
        chore.run();
        add(chore);
    }

    private void execDelayedProcedure(DelayedProcedure<TEnvironment> delayed) {
        // TODO: treat this as a normal procedure, add it to the scheduler and
        // let one of the workers handle it.
        // Today we consider ProcedureInMemoryChore as InlineChores
        Procedure<TEnvironment> procedure = delayed.getObject();
        if(procedure instanceof ProcedureInMemoryChore) {
            executeInMemoryChore((ProcedureInMemoryChore<TEnvironment>) procedure);
            // if the procedure is in a waiting state again, put it back in the queue
            procedure.updateTimestamp();
            if(procedure.isWaiting()) {
                delayed.setTimeout(procedure.getTimeoutTimestamp());
                queue.add(delayed);
            }
        } else {
            executeTimedoutProcedure(procedure);
        }
    }

    private void executeInMemoryChore(ProcedureInMemoryChore<TEnvironment> chore) {
        if(!chore.isWaiting()) {
            return;
        }

        // The ProcedureInMemoryChore is a special case, and it acts as a chore.
        // instead of bringing the Chore class in, we reuse this timeout thread for
        // this special case.
        try {
            chore.periodicExecute(executor.getEnvironment());
        } catch(Throwable e) {
            LOG.error("Ignoring {} exception: {}", chore, e.getMessage(), e);
        }
    }

    protected void executeTimedoutProcedure(Procedure<TEnvironment> proc) {
        // The procedure received a timeout. if the procedure itself does not handle it,
        // call abort() and add the procedure back in the queue for rollback.
        if(proc.setTimeoutFailure(executor.getEnvironment())) {
            long rootProcId = executor.getRootProcedureId(proc);
            RootProcedureState<TEnvironment> procStack = executor.getProcStack(rootProcId);
            procStack.abort();
            executor.getStore().update(proc);
            executor.getScheduler().addFront(proc);
        }
    }
}
